Pivotally mounted keel hydrofoil



June 13, 1967 E. 1.. MORALES PIVOTALLY MOUNTED KEEL HYDROFOIL 2 Sheets-Sheet 1 Filed Feb. 1, 1966 fm/Ewroe. Enasr L. MOEHLES 8 June 13, 1967 E. 1.. MORALES 3,324,815

PIVOTALLY MOUNTED KEEL HYDROFOIL Filed Feb. 1, 1966 2 Sheets-Sheet 2 fv vsuraz E Am Esr L. MOQHLES MMW/ flrroelve Y5.

United States Patent 3,324,815 PIVOTALLY MOUNTED KEEL HYDRGFOIL Ernest L. Morales, Los Angeles, Calif., assignor to Robert W. Pouncey, Sr., Venice, Calif. Filed Feb. 1, 1966, Ser. No. 524,330 8 Claims. (Cl. 114-66.5)

This invention relates to a hydrofoil adapted to be mounted on a boat keel and, more particularly, to a keel hydrofoil which is pivotably movable in a 180 are about its longitudinal axis.

A problem often encountered in displacement hull boats is an outside list when turning or, in the case of sailboats, a leeward list when sailing crosswind. In order to stabilize such list and also to reduce lateral drift, keels of various shapes and sizes are used. In sailboats sometimes a heavy counterweight is also added to the bottom of the keel. However, these keels cause drag resistance and add weight which tend to slow the boats.

Therefore it is a primary object of this invention to reduce the amount of drag and weight on a boat caused by the keel, but still maintain a sufficient structural capacity to stabilize the boat in order to minimize heeling, rolling, pitching and pounding.

A further object of this invention is to provide a means to increase the speed of a boat by adding a keel hydrofoil which will tend to lift the boat to a planing position.

Another object of this invention is to provide a hydrofoil which is pivotally mounted to the keel of a boat and is movable about its longitudinal center axis in a 180 are so that lateral pull on either side of the boat or vertical lift can be produced.

Other objects and advantages will become apparent from the following description and drawings wherein:

FIGURE 1 is a partly fragmented elevational view of the starboard side of a sailboat having a pivotally mounted keel hydrofoil disposed in horizontal position;

FIGURE 2 is an enlarged, partly elevational, longitudinally sectioned view of the keel hydrofoil as shown in FIGURE 1;

FIGURE 3 is an elevational view of a sailboat similar to FIGURE 1 but with the hydrofoil in vertical position;

FIGURE 4 is a cross-sectional view taken through 44 in FIGURE 3 showing a starboard list wherein the sailboat is shown heeling to a port list in dotted lines and where the keel hydrofoil is pivoted starboard in the former position and port in the latter position;

FIGURE 5 shows a schematic sectional view of a mercury inclinometer when a boat to which it is mounted lists;

FIGURE 6 is a cross-sectional view of the boat bull in FIGURE 1 taken through 66; and

FIGURE 7 is the mercury inclinorneter as in FIGURE 5 when the boat is level.

Briefly, a boat in accordance with this invention has a hydrofoil member pivotally mounted to the bottom of its keel so that its axis of rotation is horizontal and substantially parallel to the longitudinal axis of the boat. This hydrofoil member has a convex cambered surface on one side and a generally fiat or concave surface on the other side. Its pivotal mounting to the boat keel is along a centrally positioned member extending from its forward leading edge to its aft trailing edge.

The rotation of the hydrofoil can circumscribe a 180 arc from a position where the cambered surface is on the port side to where it is on the starboard side and the hydrofoil is in a plane parallel with the vertical axis of the boat in each instance. The hydrofoil can be rotated to an intermediate position where it is in a plane normal to the vertical axis of the boat. That is, the hydrofoil is then generally horizontal.

In the drawings this invention is illustrated installed on a sailboat 10 having a mast 12 supported by a hull 14. Mast 12 supports a jib 16 attached to hull 14 by jib sheet 18 and fore guy 20, a boom 22, and a main sail 24, the foot of which is secured to boom 22 which, in turn, is secured to hull 14 by main sheet 26. A conventional rudder 27 is pivotally mounted to the aft bottom portion of bull 14. Centrally longitudinally extending down from the bottom center line of bull 14 is keel 28. Extending from an aft support member 29a is auxiliary power propeller 2% which is positioned directly ahead of rudder 27.

The keel 28 does not have a weighted bottom portion, but rather has a rectangular cut-out portion 30 in its bottom which extends from a front section fore strut 32 to a rear section aft strut 34. Cut-out portion 30 is adapted so as to have enough height and length to provide sufficient room for a rectangular shaped keel hydrofoil 36 pivotally mounted between the lower rear portion of fore strut 32 and the lower forward portion of aft strut 34 to rotate therein about its central longitudinal axis. The keel hydrofoil 36 can be hollow and sealed so as to provide buoyancy or can be solid, the selection of the particular structure being dependent upon the handling characteristics of the boat though the least weight in water consistent with stability is preferable.

Keel hydrofoil 36 has a generally rectangularly shaped periphery, a fiat or slightly concave surface 38 on one side and on the opposite side a cambered convex surface 40 which is curved and tapers from its central lateral region to both its leading edge 42 and its trailing edge 44 so as to provide a hydrodynamically shaped member best seen in cross-section in FIGURE 2.

Thus, when it is moved forward through water it hydrodynamically causes a pressure differential to be created between cambered surface 40 and the opposite side surface 38. The greater pressure is on surface 38 which tends to increase with increasing speed so as to develop a pull or lift on cambered surface 40.

Extending centrally and longitudinally within hydrofoil 36 so as to provide a beam support from leading edge 42 to trailing edge 44 is a pivot axle 46 which preferably tapers fore and aft to conform to the hydrofoil curvature. It is secured to a crank arm 48 near leading edge 42 and to a bent shaft '50 near its trailing edge 44. A forward shaft 49 which is connected at the other end of crank arm 48 and an aft portion of bent shaft 50 are, in turn, pivotally supported and substantially parallel with the longitudinal center line of boat hull 14. They are journaled within respectively, forward bearing 52 in fore strut 32 and aft bearings 54a and 54b in aft strut 34. Bearings 52, 54a and 54b are mounted near enough to the bottom of their respective struts that keel hydrofoil 36 will clear keel 28 when rotated within cut-out portion 30 therein. Accordingly, the height of cut-out portion 30 must be somewhat greater than one-half the width of keel hydrofoil 36 since a lateral half of hydrofoil 36 is swung through cut-out portion 30 when hydrofoil 36 is rotated between its starboard and port positions.

The desired angle of attack of the leading edge 42 of hydrofoil 36 relative to the longitudinal axis of hull 14 is determined by the length of crank arm 48. This crank arm 48 also defines the radius of the arc of rotation for the forward part of hydrofoil 36. Since no comparable extended portion projects from rear shaft 50 pivot axle 46 subscribes a conical are which tapers aft when rotated. Thus, the amount that shaft 50 needs to be bent between aft bearing 54a and its attachment to the aft end of pivot axle 46 to allow hydrofoil 36 to smoothly rotate is dependent upon the angle of attack of leading edge 42. The optimum angle of attack and the particular shape of hydrofoil 36 will vary in accordance with the hydrodynamic requirements of the boat to which it is mounted.

Typical positions of the keel hydrofoil 36 when it is pivoted within its 180 are are 'best seen in FIGURES 4 and 6. In FIGURE 4 hydrofoil 36 is outboard and parallel with the vertical axis of keel 28 with cambered surface 40 facing starboard in the full line drawing and port in the dotted line sketch. On the other hand hydrofoil 36 is normal to the vertical axis of keel 28 with its cambered surface 40 up in FIGURE 6. The mounting of hydrofoil 36 on L-shaped pivot arm 48 near its leading edge 42 positions edge 42 outboard of keel 28 when vertical so as to permit a greater hydrodynamic pull than if directly aligned behind the fore strut 32 of keel 28.

In order to control the inclination of hydrofoil 36 a helmsmans Wheel 56 is rotatably mounted to support member 57 within hull 14. This wheel 56 is adapted to turn pivot axle 46 through meshed reduction gears 58a and 58b which, in. turn, rotate connected chain sprocket 580 which drives chain 58d and driven sprocket 582 mounted on shaft 50. Thus, by turning wheel 56 the inclination of hydrofoil 36 is changed. A suitable locking means, such as pawl 59a pivotally mounted on support member 57 and controlled by connected handle 59b so as to be engageable with gear 58a is provided in order to hold the hydrofoil 36 in a desired position and chain 58d can :be spring tensioned to counteract backlash if necessary.

The chain driven mechanism shown is a convenient means for conserving space in the drive structure so as to allow minimum keel thickness. However, other means such as beveled gears, rotatable shaft linkage and motor drives could be used to adjust the inclination of hydrofoil 36. The driven shaft could be either or both rear shaft 50 as shown or forward shaft portion 49 of crank arm 48 with suitable modifications thereto.

Moreover, it may be found that the hydrofoil 36 is subjected to such stress and strain when in use that universal joints are preferred as connections between the rear of pivot axle 46 and rear shaft 50 so as to eliminate the bent portion of the latter.

In order to provide a precise control of the hydrofoil inclination the means for locking the hydrofoil 36 in a particular inclined position can be arranged so that the lock positions are predetermined incremental parts of the 180 arc of rotation such as on each degree thereof. Preferably, hydrofoil 36 should at least be lockable in its horizontal position and its two vertical positions on each side of keel 28.

If the hydrofoil 36 is rotated :by a motor (not shown) instead of manually it may be desirable to automatically adjust the inclination of hydrofoil 36. A method by which this can be done is to use an inclinometer 61 mounted on deck 62 which includes a vessel 64 partially filled with liquid mercury 66. Protruding down from a cover 68 for vessel 64 are a series of electrical contacts 70, 72, 74, 76, 78 and 80 which extends varying distances down toward the level of the liquid mercury 66 and are generally aligned athwartship of the hull 14. Three separate circuits can be completed between pairs of these electrical contacts through their respective lead wires 70', 72, 74, 76', 78' and '80. That is, circuits are completed between lead wire 70 and 72', between lead wires 74 and 76, and between lead wires 78 and 80'. The circuit which includes lead wires 70' and 72' actuates the motor driven hydrofoil mechanism so as to rotate hydrofoil 36 to a vertical position on the same side as the mercury is tilted. In a like manner the circuit which includes lead wires 7 8' and 80' actuates the hydrofoil motor so as to rotate hydrofoil 36 in the opposite direction to a vertical position and the circuit which includes lead wires 74' and 76' actuates the hydrofoil motor so as to rotate hydrofoil 36 to a horizontal position.

These electrical contacts are designed to give a read-out in accordance with the amount that the level of mercury 66 tilts which, in turn, corresponds to the list of the boat. Thus, if the boat is level the mercury 66 in inclinometer 61 will be level as in FIGURE 7 and only contacts 74 and 76 not contacts 70, 72, 78 or 80, will touch the surface of mercury 66 so as to complete a circuit through lead wires 74 and 76' and position hydrofoil 36 horizontally. On the other hand, when the boat tilts, as in FIGURE 5, electrical contacts 76, 78 and 80 touch mercury 66 not contacts 70, 72 or 74. Thus, a circuit is completed through lead wires 78' and 80' which actuates the hydrofoil motor drive so as to rotate hydrofoil 36 to a vertical position on the same side as the list. In a like manner other angles of list can be indicated by such a device.

If the hydrofoil 36 is manually rotated the circuitry from inclinometer 61 can be connected to a scaled instrument (not shown) which can be read by the boat navigator so as to advise him of the amount of list. Thus, he can gauge how much to adjust the tilt of the keel hydrofoil 36 to counteract the degree of list.

The advantages of this invention should be apparent from the preceding description. Thus, a person having a sailboat equipped with the hydrofoil 36 as described would find that when his boat begins to list to starboard he could tend to right the boat by turning the helmsmans wheel 56 so as to rotate the hydrofoil 36 so as its cambered surface 40 is starboard as in FIGURE 4 and conversely rotating the hydrofoil 36 to port when the boat lists to port as in the dotted lines in FIGURE 4.

On the other hand if the boat is sailing before the Wind or into the wind without significant list the hydrofoil 36 should be rotated to its intermediate horizontal position as in FIGURE 6 where the cambered surface 40 is up. This horizontal position is also useful as a means for reducing the draft of the boat when in shallow water or when it is being trailered or is in dry dock. When under way the hydrofoil turned to its horizontal position tends to lift the boat toward a plane and reduce the wetted sur face of the hull so that increased speed can be attained. The lateral extensions of the hydrofoil in this horizontal position also tends to stabilize the rocking and pitching motion of the boat.

In addition to the horizontal and vertical positions of the hydrofoil it preferably can be locked in a number of intermediately inclined positions so as to provide a precise means for adjusting it to its optimum position.

Though the description has been concerned with a sailboat adapted to use this unique hydrofoil pivotally mounted on its keel this was meant to be illustrative only as this hydrofoil invention can be equally useful for a conventional power boat, particularly displacement type ships which are intended to run fast and turn quickly such as coast guard cutters, submarine chasers and destroyers. In such ships the hydrofoil would 'be mounted to the keel substantially as shown relative to the sailboat. Since it would be larger it would necessarily require a more rugged structure and probably a power operated turning mechanism instead of the manually openated helmsmans wheel.

By utilizing this hydrofoil keel invention a boat can have a flatter bottom than normally would be required and thereby facilitate planing and provide better lateral stability.

While the particular pivotally mounted keel hydrofoil herein shown and described in detail is fully capable of attaining the object and providing the advantages hereinbefore mentioned, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. A boat having a fixed keel protruding longitudinally down from the bottom of said boat along the center line thereof, said fixed keel including a fore strut portion and an aft strut portion spaced apart so as to define a central cutout portion in the bottom of said fixed keel, a hydrofoil member having a cambered surface, means for pivotally mounting said hydrofoil member between said fore and aft strut portions in such a manner that it can be rotated substantially 180 within said cutout portion between a vertical position where the cambered surface is starboard and a vertical position Where the cambered surface is port, and means for rotating said hydrofoil member.

2. A boat as in claim 1 wherein the hydrofoil member is pivotally mounted to the fore strut portion by means of a crank arm which inclines the leading edge of the hydrofoil member at the optimum angle of attack and to the aft strut portion by rotatable shaft.

3. A boat as in claim 1 wherein the central cut-out portion in the fixed keel is slightly greater than one-half the width of the hydrofoil so as to provide room for said hydrofoil to be rotated and swung through said cut-out portion.

4. A boat as in claim 1 wherein the means for rotating the hydrofoil is linked to a manually controllable wheel on the boat deck which can be locked in fixed position.

5. A boat as in claim 1 which includes an inclinometer and wherein the means for rotating the hydrofoil is actuated by the inclinometer so that its inclination is automatically adjusted in accordance with the direction of boat list registered by the inclinometer.

6. A boat having a fixed, longitudinally extending, downwardly protruding keel, said keel having a cut-out bottom portion extending between a front section and a rear section thereof, a hydrofoil slightly shorter than the length of said keel cut-out portion and slightly narrower than one-half the depth of said keel cut-out portion, said hydrofoil having one surface longitudinally cambered, pivotal means for longitudinally centrally mounting said hydrofoil between the front and back sections of said keel so that it can pivot freely within said cut-out portion of the keel in a are wherein the cambered surface of said hydrofoil is up when normal to the vertical axis of said keel and outboard when inclined from said normal position, means for rotating said hydrofoil and means for securing said hydrofoil in a predetermined position.

7. A boat as defined in claim 6 which includes a pivot axle extending centrally and longitudinally within the hydrofoil so as to provide an axis of rotation for said hydrofoil wherein the forward part of said pivot axle is pivotally mounted to the lower rear front section of the keel by means of a crank arm and forward axle, and the rear part of the pivot axle is pivotally mounted to the lower front back section of the keel by means of a rear axle adapted to compensate in alignment for the projection of said crank arm so as to allow free rotation of said hydrofoil in a conical arc tapering aft, the radius of which is determined by the length of said crank arm thereby providing the hydrofoil with a predetermined optimum angle of attack.

8. A boat as defined in claim 6 wherein the hydrofoil is an air-tight sealed structure which is buoyant in water.

No references cited.

MILTON BUCHLER, Primary Examiner.

A. H. FARRELL, Assistant Examiner. 

1. A BOAT HAVING A FIXED PROTRUDING LONGITUDINALLY DOWN FROM THE BOTTOM OF SAID BOAT ALONG THE CENTER LINE THEREOF, SAID FIXED KEEL INCLUDING A FORE STRUT PORTION AND AN AFT STRUT PORTION SPACED APART SO AS TO DEFINE A CENTRAL CUTOUT PORTION IN THE BOTTOM OF SAID FIXED KEEL, A HYDROFOIL MEMBER HAVING A CAMBERED SURFACE, MEANS FOR PIVOTALLY MOUNTING SAID HYDROFOIL MEMBER BETWEEN SAID FORE AND AFT STRUT PORTIONS IN SUCH A MANNER THAT IT CAN BE ROTATED SUBSTANTIALLY 180* WITHIN SAID CUTOUT PORTION BETWEEN A VERTICAL POSITION WHERE THE CAMBERED SURFACE IS STARBOARD AND A VERTICAL POSITION WHERE THE CAMBERED SURFACE IS PORT, AND MEANS FOR ROTATING SAID HYDROFOIL MEMBER. 